The inhibition of cathepsin S by its propeptide--specificity and mechanism of action.
The interaction of human recombinant full-length cathepsin S propeptide (amino acids 16-114) with mature cysteine proteinases was studied with respect to selectivity and pH dependence. The inhibitory capacity was tested towards mature human recombinant cathepsin S, purified cathepsin L from rat and Paramecium tetraurelia, rat cathepsin B, human cathepsin H, and papain. The propeptide of cathepsin S strongly inhibited cathepsin S (Ki = 0.27 nM) and the two cathepsin L species (Ki = 0.36 nM) at neutral pH. Papain, and to a minor extent cathepsin H, hydrolyzed the propeptide of cathepsin S, leading to competition with the hydrolysis of the fluorogenic substrates in the respective assays. Cathepsin B activity was nearly unaffected up to micromolar propeptide concentrations in the assay. The inhibition of cathepsin-L-like peptidases was diminished with decreasing pH, probably due to dramatic changes in the conformation of the propeptide. This assumption was supported by far-ultraviolet CD spectroscopy and by the finding of rapid hydrolysis of the cathepsin S propeptide by cathepsin L at pH values less than 5.5.
Maubach
G
G
Institut für Biochemie I, Klinikum der Friedrich-Schiller-Universität, Jena, Germany.
Schilling
K
K
Rommerskirch
W
W
Wenz
I
I
Schultz
J E
JE
Weber
E
E
Wiederanders
B
B
D000818:Animals; D016367:Baculoviridae / Q000235:genetics; D002403:Cathepsins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D002942:Circular Dichroism; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007700:Kinetics; D010206:Papain / Q000037:antagonists & inhibitors; D010247:Paramecium / Q000201:enzymology; D010446:Peptide Fragments / Q000737:chemistry / Q000494:pharmacology*; D011485:Protein Binding; D011487:Protein Conformation; D011498:Protein Precursors / Q000378:metabolism; D051381:Rats; D011994:Recombinant Proteins / Q000235:genetics / Q000494:pharmacology
D015853:Cysteine Proteinase Inhibitors; D010446:Peptide Fragments; D011498:Protein Precursors; D011994:Recombinant Proteins; D002403:Cathepsins; D010206:Papain; C028217:cathepsin S